How to make a permanent spot of light in a characters eyes?
To find the right materials and light setup so you can replicate this look I recommend the following tutorial: https://www.youtube.com/watch?v=nPK6JlWESM8

For Anime-Style Chractere it looks better to take a .png/.jpg file, split it into white/transparent and attach it to the armature of the iris. VRoid has some complete models ready for download free of charge.